Quad Core Optimization

in a game optimized for quad core, what dual core cpu will be needed to match a 2Ghz quad core's performance? and in a game not optimized for quad core, which dual core's clock speed will the quad cores performance match? will there be any increase at all without taking advantage of quad core?

 

If an app is single threaded, no additional cores will give you any benefit (except if you are running other apps in parallel). If an app has 2 threads, it will be able to utilize a dual core proc. If it is truely multithreaded, the app will utilize as many cores as it is able. There aren't really one to one calculations on parity between different core count chips, as depending upon how the app is programmed, running a multithreaded app can incur more or less (though all will incur some) thread management (especially thread swapping) overhead on a CPU with fewer cores than the program has threads.

 

if the game is optimized for quads truly, then no dual core will match the quad. You will need a crazily overclocked dual to get in sync with the quad and the speeds im talking about are impossible in the current penryn core2's

 

If a game was perfectly optimized for a quad then a 2ghz quad should be evenly matched with a 4ghz dual. Or at least that's what I would expect.

 

no more cores will beat a core 2 thats twice as fast clockspeed wise in a game that is optimized for 4 cores. More cores is def greater than double clock speed. Play GTA4 with a 5ghz dual core on a desktop and then play with a 2.5ghz Quad core. it will play better with the quad....and that game is poorly optimized overall

 

That's incorrect. You're forgetting to account for thread swapping overhead. To match a fully utilized 2GHz quad, you'd need something like a 4.4GHz or 4.8GHz dual. Of course, few games fully utilize even a dual (including games optimized for a dual), but the same basic idea applies.

 

Where do you find these 5GHz dual cores?

Honestly though, I agree with all posters beforehand.

If a game is optimised for quad core then it means it's been coded with four separate threads to be run at the same time. For a dual core to be better it would need to be ridiculously fast.

 

hahah you cant find a 5ghz dual core but u certainly can overclock to that with the new desktop core i7's

 

Some people still claim that GTA IV does not take advantage of Quads lol

http://www.youtube.com/watch?v=fadvAJ1_2eA

GTA IV is a strange one because sometimes it seems that I get the same performance with 2 or 4 Cores but other times it seems slower with 2 Cores disabled and then I lose fps using one particular Nvidia Driver when compared to the other.

Some say they get good performance on a 2.8 Ghz Core2Duo with GTA IV. I would like to see benchmarks of GTA IV in game of 2 Cores Vs 4.

Later on I will do some testing on GTA IV with my Q9000 comparing in more detail 2 Cores Vs 4 Cores.

 

thread swapping? meh.

from the same generation of processors, running a "perfectly" quad-core optimized game, a 4Ghz dual core will operate the same as a 2Ghz dual core.

sure, you have thread swapping, but also, as you expand to more cores, your optimal usage of them gets less and less (ie. you can't fill all the cores all the time)

either way, its going to be really really close between a 4Ghz dual core and a 2Ghz quad core.

 

...and hence why I said 100% utilizied, masterchef. And no, a "perfectly" optimized 3+ thread game will not run equally on a double speed dual when compared to a quad. It will be pretty close, as you said, but it won't be the same. You need an extra 5%-20% more power depending upon architecture to equal the performance, assuming 100% utilization.

 

i agree that if you take an application that fully utilizes 100% of all 4 cores, that you would need a *slightly* faster than double speed dual core machine to handle the same load. i think 5% is more realistic than 20%.

a perfectly optimized quad core game does not mean 100% utilization on all cores afaik.

 

No, it doesn't necissarily, however, even if threads sit in waiting state for 80% of the game loop, if the game is relying on them running with maximum concurrency for the 20% of the game loop they are active, then you will still get thread swapping latency, whether or not you have 100% utilization averaged over an arbitrary length sampling window. And depending on architecture of both the chip and the software, you can see extensive losses due to swapping. I think (purely gut feel admittedly) that modern procs are somewhere around the 5%-10% overhead range for something like we are talking about though.

 

do you think the number of games optimized for quad core will significantly increase in the next 2 or 3 years? whats the best choice right now, a slower quad or faster dual core? and what games, available and planned, will be optimized?

 

In my test the two most expansive cpu tests I can think of is Wprime and Video Encoding, I find that the quad core is almost exactly 2x faster than the same speed dual core.

 

you should check out the scores in CPU testing that I am doing with the Core i7 975 in the Clevo D900F...

Even pushed it to 4.0 GHz (133 x 30 multiplier) ....



No other notebook on the market is gonna touch that for a long time....

 

Yea, those are the most parallel of the parallel coded applications you can find. In games, no quad will match a 2x clocked dual. Unlike a quad, 2x clocked dual doesn't have as much conflict sharing resources like memory bandwidth and cache. Things like cache snoops and communication between the cores will bottleneck the quad cores far before it ever reaches the performance of having double the amount of cores will give you.

Amdahl's Law says that the speedup of a parallel program is limited by the amount of serial code in the program.

If everything was so easily parallelizable as we would like, we wouldn't have been sitting with 3-issue processors and single cores for most of the last 10 years.

In reality, most of the parallel program would give quad cores the performance equivalent of a 70% higher clocked dual core. Clock speed increases give around 80% scaling. Core increases give around 50-60%. Multi-tasking maybe. Pure performance on a single app, never.

 

yeah that i7 is crazy fast, would be great for video work, but I took the dual 4870's in the W90 for the game power.

I can walk away from my laptop while it encodes a video, if it takes longer to encode I go do something else (or since I have a quad core it can run while I do other things)

but if your at your gpu limit in a game and the D900F is half the frame rate say 20fps vs 40fps thats the difference between playing a game and not. You cant just wait that out or walk away for a while

Plus the W90 was cheaper, also doesn't he D900F have some heat issues?

 

But whats it matter if my quad is giving me 70% load and your dual is at 40% load the performance in the game is the same.

Its when the cpu is maxed out that it matters, and so far the games most cpu bound tend to be quad core optimized (Supreme Commander, FSX, etc)

Even if you did find a situation where the quad has 2 cores maxed out @ 100% in a game and the dual is 100% or less whats it going to matter if I am already at like 90fps and your at like 120fps?? the performance and gameplay are going to be the same.

In real life testing a 2.0ghz on a quad is enough to max out 95% of all modern games, 2.4ghz is enough for 99.9% of games. I have benches in the W90 review showing 2.0 vs 2.3ghz to show there was no improvement because @ 2.0ghz the game was already maxed out and not needing more cpu power.

 

no heat issues...

GPU is ice cold and never exceeds 70C at max load (FurMark even couldnt get it warmer than 75C for 30min)

CPU, however, is running pretty warm (well for the Core i7 Extreme 975 it is)... the desktop Core i7's are hot for sure... still surprised that Clevo still was able to use it in a notebook and keep temps around 55-60C at idle and up to 80C at full load.

My OC'ing of the Core i7 975 brought it to 100C at times... LOL.

Now to figure out how to undervolt the thing, then we have a fast and cool beast on our hands.

 

The last time I read, lots of the pure gamers went for higher clocked dual core over a quad core. Quad core might give you better performance in the future in "theory", but by the time that's relevant there will be dual cores that will beat the quad core in everything anyway.

According to Intel data, Core i7 Bloomfield platform takes 1% of the total marketshare, while the dual core Clarkdale will take significantly higher 10% in the first quarter of its introduction.

Anyways, if you cared so much about performance, you wouldn't be running background tasks for the fear of slowing your game down anyway, quad or not.

Windows bounces threads around its multiple cores for the reason that in the single core days, it was better for multi-tasking. With Windows 7, it won't do that anymore and stop bouncing threads around.

Of course, your example is pretty poor because most of the time(some poor code app might be different), 40% load on a dual core would end up to be something around 20% on a quad, not 70% on a quad and 40% on a dual.

 

90 fps vs. 120 fps:

I have seen competitive league gamers using simple textures for the sake of eliminating non-network lag with their SLI/Crossfire based systems and overclocked CPUs.

Unlike video or movie, games do not run at fixed frames per second all the time. The reason for higher performance is to decrease the situations where minimum frames might kill you(might be true in games literally ).

Some still care squeezing that extra performance(that number), or otherwise Core i7 would have been THE CPU to get for gaming systems because of the combination of multi-threading per core, excellent core performance and dramatically increased memory bandwidth gives you.

But its not. Like I said, 1% of total shipments are Core i7.

 

Your very wrong, the debate most use is how games do not support quad core only 2 cores. And the clock speed is lower on the quad.

So given that if you had say a 2.4ghz quad and a 2.8ghz dual, the load would be higher on the cores on the quad than the dual core cpu.

Also my example is not poor at all its real life, sales dont mean anything at all about the performance, that just means they got the dual core because it came with there computer, or because it was cheaper, or they were not educated enough to know the quad core was better.

Highly educated tech heads like myself are a rarity not the majority.

Go ahead and join the majority, but atleast you had the opportunity here to learn something and you chose not to.

 

Yeah i7 is brand new, you need a new mobo, new ram, and a new cpu to use it, too much cost for the average person. If we start a poll here in the forums for anybody that built there own computer in the last year or so I bet core2quad is going to be just as common as core2duo.

 

I heard that statement so many times from resellers, gamers and general forum users too.

Resellers were saying ''get a higher clocked Core2Duo because hardly any games are Quad optimised, they are Dual optimised and the 2.0 Ghz clock in the Q9000 is too slow and you will not get good gaming performance''

Other statements I heard are "A Core2Duo will give you better gaming performance than the Q9000''

The answer to most of those comments can be found in my Q9000 performance thread. I don't understand why they convince themselves that a higher Clocked CPU will give better performance when the CPU is not the deciding factor at the resolution being used in most cases.

The fact is, getting a 2.0 Ghz Q9000 now will give you great gaming performance and also the potential of good performance in any Quad optimised games now and in the near future. If you don't have any battery time concerns then there is no reason not to go for one.

I always use my laptop plugged in so I have no idea about battery time, I just assume it will be shorted than a Core2Duo.

 

Yes lots of resources on how well the Q9000 runs, and keep in mind the Q9000 on my W90 overclocks to 2.7ghz!

But you cant convert them all, all you can do is share the knowledge and them let them decide for themselves.